Waec Chemistry 2005 Past Questions and Answers

Question 1:

• WAEC 2005

The electronic configuration of an element X is 1s²2s ²2s⁶3p ² 3p⁴. It can be deduced that X

A. Belongs to group 6 of the Periodic Table
B. Belongs to group IV of the Periodic Table
C. Has 3 unpaired electrons in its atom
D. Has relative molecular mass of 16

Question 2:

• WAEC 2005

The electronic configuration of an element X is 1s²2s ²2s⁶3p ² 3p⁴. It can be deduced that X

A. Belongs to group 6 of the Periodic Table
B. Belongs to group IV of the Periodic Table
C. Has 3 unpaired electrons in its atom
D. Has relative molecular mass of 16

Question 3:

• WAEC 2005

What is the mass number of an element having 20 neutrons, 15 protons and 15 electrons?

A. 15
B. 30
C. 35
D. 50

Question 4:

• WAEC 2005

Which of the following sets of elements are arranged in order of decreasing atomic size in the Periodic Table?

A. ₆C, ₄Be, ₇N,₈ O
B. ₄Be,₆ C,₇ N,₈ O
C. ₈O, ₇ N, ₆C, ₄Be
D. ₇N, ₈O, ₆C,₄BeBe

Question 5:

• WAEC 2005

Which of the following changes is characteristic of an alpha-particle emission?

A. The nucleus loses two protons and two neutrons
B. A proton combines with an electron giving off heat
C. The nucleus splits into two equal parts
D. Four neutrons are lost